[MacRuby-devel] XCode 4 error

Hi folks, I must be missing something really simple. I'm running Lion, Xcode 4.1, and the latest MacRuby. When I open a project and try to build it, it gives an Embed issue: "Shell Script Invocation Error. Command /bin/sh failed with exit code 1." It isn't like I don't have sh on my system. Thoughts?